Preparation of okara cellulose nanofibers and arabic gum composite hydrogel using sonication: Structure, rheology and potential application in sustainable food packaging

Okara (soybean residue) cellulose is an abundant natural polymer with broad development prospects due to its low-cost and biodegradable properties. In this study, the composite hydrogel was fabricated by combining cellulose nanofibers (CNFs) and Arabic gum (AG) through hydration, oil bath heating at 90°C, sonication, and low-temperature treatment. The effects of TEMPO oxidation and AG addition on the structure and properties of the composite hydrogel were also investigated, including its microstructure, thermodynamic properties, rheological properties, surface properties, and texture properties. The hydrogel showed new absorption peaks at 842, 925 and 1225 cm −1 , low-crystallinity (61.7%) and low-oxygen carbon ratio (0.56), which confirmed strong intermolecular interactions (including hydrogen bonding and electrostatic forces) occurred between CNFs and AG, forming a robust gel-like network. The thermal stability, surface properties, and texture properties of the composite hydrogels, such as their degradation temperature (213.7°C) and the contact angle (33.1°), the interfacial tension (50.4 mN/m), cohesiveness (0.95) and gumminess (289), could be optimized by controlling the TEMPO oxidation, AG concentration and sonication. The developed okara CNFs-AG composite hydrogel exhibits significant potential as a safe, sustainable, and eco-friendly material for innovative food packaging and delivery systems.